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Making a battery cigarette lighter

  1. Oct 7, 2012 #1
    I read an article in prison inventions and was impressed by some of the things the inmates MacGyvered. A very simple invention I saw though was a cigarette lighter made from a battery:
    prison-battery-lighter.jpg
    I have an understanding of basic electronics theory but I have very little practical experience. I can see a piece of thin wire connected to the insulated copper wire, obviously thats the heating element but what material would you say that is? Am I right in assuming that a material for a heating element needs to be far less conductive than conductive metals like copper or aluminum?

    I did an experiment in which I made a broken circuit with some aluminum foil. I completed the circuit with a piece of tissue paper (a single width) and was expected the tissue to go on fire but it didn't. I know tissue is completely non conductive but I thought that 1.5V would overcome the resistance the tissue is about a micrometer wide. I accidentally completed the circuit at one point and I was holding the foil to each terminal with fingers and I rapidly felt a burning sensation on my fingers so I know the battery has voltage in it. Why didn't the tissue ignite?
     
    Last edited: Oct 7, 2012
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  3. Oct 7, 2012 #2

    phinds

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    Re: Making a battery lighter

    Well, less conductive than a normal sized wire, yes, but one COULD achieve that with a REALLY thin strand of copper. Of course it would likely melt immediately. But yes, your basic thought is correct.

    Why would you expect even thin tissue to conduct electricity at 1.5 volts? If you had maybe a molecule's thickness, yes, or if you had enough voltage to overcome the resistance, yes (although in that case I could expect a spark, not real conduction)
     
  4. Oct 8, 2012 #3
    Re: Making a battery lighter

    Thanks, that clears up my questions. One thing I'm still wondering though is why my fingers heat up if I hold a strip of aluminum foil to both terminals of the battery. The burning sensation on my fingers gets very intense in a matter of seconds. I don't feel any burning if I complete a circuit by holding two pieces of wire together with my fingers. I'm guessing what I'm feeling is electricity itself, not heat generated by the circuit. Is some of the current travelling through my skin (and thus heating the skin up)?

    Also, do you know what material the heating element in that prison lighter could be made of? In this video:

    the guy makes the same type of battery lighter but I don't understand where he gets the heating element from. I see that he disassembles a kettle but where does that piece of wire come from? All the kettles I've seen have heating elements like this:
    http://www.sciencephoto.com/image/221343/530wm/H1300610-Kettle_electric_heating_element-SPL.jpg
    I don't understand what that piece of wire he salvaged from the kettle is.
     
    Last edited by a moderator: Sep 25, 2014
  5. Oct 8, 2012 #4

    davenn

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    Re: Making a battery lighter

    well you are shorting out the battery and the foil is conducing all the current that the battery is able to supply. The foil is getting hot as a result and transferring that heat to your fingers

    if you hold a bit of copper wire between the terminals of the battery , the same thing will happen. But you didnt specify that

    what sort of circuit were you completing ? if its anything more than one thats close to a short circuit, then no, you wont feel the wire joint getting hot
    ( will qualify that by saying that it may get warm/hot if really high currents are involved)
    That is because there would be a small amount of resistance in a mechanical joint that wouldnt be there in say a soldered joint

    Dave
     
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